Consider the following protected class containing a public method.
package my.package;
class MyClass {
  public void myMethod() {
    // myMethod implementation
  }
}
Since MyClass is not marked as public, it therefore has protected access and thus is not accessible outside the package. However, its method myMethod is marked as public, signifying that it is accessible outside the class.
Since myMethod presumably cannot be accessed without accessing MyClass, why is it possible to mark myMethod as public? Is it because someone might extend MyClass from within the package, with a custom public class for use outside the package? For example:
package my.package;
public MyPublicClass extends MyClass {
  // MyPublicClass implementation
}
If so, is there any other use for a public method defined within a protected class?